TR33 in the Light of the US-Dark Energy Task Force

Report

Thomas ReiprichDanny HudsonOxana NenestyanHolger Israel Emmy Noether Research GroupArgelander-Institut für AstronomieUniversität Bonnhttp://www.dark-energy.net

US-Dark Energy Task Force (DETF)

• Established to advise DoE, NASA, and NSF on future of dark energy research.

• Members: Kolb, Albrecht, Bernstein, Cahn, Freedman, Hewitt, Hu, Huth, Kamionkowski, Knox, Mather, Staggs, Suntzeff.

• US - why care? Useful calculations, trendsetter.

Introductory Remarks

• DE one of most important problems in all physical sciences.

• Most critical component of any approach to DE problem is improvement in experimental constraints.

• Clear steps can be taken to drive significant progress.

Four Main Techniques• Baryon Acoustic Oscillations (BAO; new, less

affected by astrophysical uncertainties but least statistical power).

• Galaxy Cluster (CL) surveys (MF, statistical power to exceed BAO and SN but currently largest systematic uncertainties).

• Supernova (SN) surveys (at present most powerful).• Weak Lensing (WL) surveys (new, if systematics

under control as currently predicted then most powerful technique).

• No primary CMB. GRBs and GW unclear.

Four Stages

• I: Known today.

• II: Known after completion of ongoing projects.

• III: Currently proposed near term projects.

• IV: LST, SKA, JDEM.

Recommendations

• Multiple techniques at every stage, at least one sensitive to growth of structure.

• Stage III projects should achieve factor 3 gain over stage II projects.

• Stage IV factor 10.• High priority for near term funding for

studies of systematic efffects.

Goals, Figure of Merit

• Accelerated expansion due to cosmological constant?

• If not, constrain w(a) (= w0+(1-a)wa).

• Check for inconsistency between w(a) from cosmic expansion and growth of structure (i.e., possible failure of general relativity).

• Figure of merit: 1/area of 95% error ellipse in w0/wa plane.

Direct Relation to TR33

• All observational methods included!– BAO: B8– CL: B4, B6, B7 (optical, SZ, X-ray, lensing)– SN: B3– WL: B5

Direct Relation to TR33

• “Our inability to forecast systematic error levels reliably is the biggest impediment to judging the future capabilities of the techniques.” => Use results with care. => Test systematics.

Direct Relation to TR33

• TR includes (almost?) all mentioned primary tests for systematics for all techniques:– BAO: better theoretical understanding of non-linear

regime and bias (B8, C1).– CL: observational constraints from lensing, SZ, and

X-rays on observable-mass relation (B6, B7).– SN: detailed observations of nearby SN to study

dependence of peak luminosities (and spectra) on observational parameters (B3).

– WL: observational calibration of photo-z technique (also for BAO) and study feasibility of corrections for intrinsic galaxy shapes and PSF (~B5, B8?).

Direct Relation to TR33

• Involvement in– JDEM?– LST?– SKA?